Hydraulic fluids are usable in blowout preventer (BOP) devices to control well-head pressure of a well that is being drilled and/or in marine environments. A “blowout” is defined as uncontrolled flow of gas, oil, or other well fluids out of an underground formation. A blowout can occur when formation pressure exceeds the pressure applied to it by the drilling or extraction apparatus. A BOP is a specialized valve, usually installed redundantly, in series, to seal, control and monitor oil and gas wells. The BOP is actuated by hydraulic pressure that forms a seal around the drill string to seal off well head pressure when an area of high pressure has been contacted.
There are several challenges for the fluid which delivers the hydraulic pressure. For example, use of conventional hydraulic fluids can be complicated by low flash points and poor fire resistance. Also, toxicity, bioaccumulation, and biodegradation of conventional fluids can lead to environmental concern as well as lead to bacterial infestations arising in the fluid, especially from anaerobic bacteria such as sulfate reducing bacteria which are prevalent in sea water. Another challenge with conventional fluids is compatibility with sea water which often leads to emulsions or precipitation. Corrosion is also a concern and, in general, long term stability of the fluid at elevated temperatures with the entire system which is contacted by the fluid.
What is needed in the art is a BOP hydraulic fluid which addresses all of these concerns and at the same time provides adequate lubricity and wear characteristics.